Process of making alumina and by-products.



PATENTED Nov, 24,1903.

. L. R. KEOGH. noosss 0P MAKING ALUMINA AND BY-PRODUOTS.

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0 UNITED. ST TES Patented November 24, 1903. I

P T NT @FFIQEQ LUCIUS RIOl-IAR'DKEOGH, or PEMBROKE, CANADA, ASSIGNOR orONE- THIRD TO NOAH JOSEPH GAREAU, or PEMBROKE, CANADA.

PROCESS OF MAKING ALUM'INA AND BAY-PRODUCTS.

sPECIFIGATION forming part of Letters Patent No. 744,765, dated November24, 1903.

K Application filed August 13, 1902. Serial No. 119,502. (No specimens.)

To all whom, it may concern."

Be it known that I, Lucius RICHARD KEOGH, a subject of the King of GreatBritain, and a resident of Pembroke, in the county of Benfrew, Provinceof 'Ontario, and Dominionof Canada, have invented new and usefulImprovements in the Manufacture of Alumina and By-Products, of whichthefollowingis a full, clear, and exact description.

The object ofthe invention is to provide a new and improved process forthe manufacture of alumina and by-products, such as bydrochloric acid,sodium sulfate, sodium aluminate, sodium carbonate, and other sub--stances that may be contained in clay, kaolin, bauxite, or'otheraluminous ores, sulfate of aluminium, or other aluminous materials to betreated, and sodium chlorid.

The process consists, essentially, in mixing sulfate of aluminium withsodium chlorid and some water to form a thick pulp, then heating thelatter and passing steam into the pulp to form a mixture of alumina andsodium sulfate and to evolve gaseous hydrochloric acid with steam, andfinally separating the sodium sulfate from the alumina.

In carrying out the process I prefer to use an apparatus such as shownin the accompanying drawings, forming part of this specification, inwhich similar characters of refer-' ence indicate corresponding parts inboth views.

Figure l is a sectional side elevation of the apparatus for treating.comparatively pure sulfate of aluminium, and Fig. 2 is a like View ofthe apparatus for treating impure sulfate of aluminium. v

The apparatus shown in Fig. 1 consists, essentially, of a'vessel A,arranged in a brickwork B and heated from the products of combustion ofthe burning fuel held on the grate C of the furnace D, carrying asteam-boiler E. The brickwork is provided with an outlet-flue B. Thevessel, A is connected by a pipe F with a condensation-chamber G, andinto the vessel A extend the steam-pipes H; receiving their supply ofsteam from the boiler E. The vessel A is provided with a charging-door Afor placing the material to be treated into the vessel, and the latteris also provided with doors A forremoving the final In detail I proceedas follows: Sulfate of aluminium, preferably hydrated sulfate ofaluminium or hydrated acid sulfate of alu 'minium of the formula Al (SO.16H O, and

sodium chlorid in a quantity equivalent chemically to the sulfuric acidcontained in the sulfate of aluminium are thoroughly mixed with somewater to form a pulp, which is placed in the vessel A and graduallyheated therein to about 200 to 300 centigrade, and

at the same time steam is passed into the pulp by the pipes'H, so thathydrochloric acid is formed, which passes with the steam through thepipe F to the condensation-chainber G to be condensed therein, whilealumina and sodium sulfate settle in the vessel A and are removed fromthe same to suitable washing-tanks to dissolve the sodium sulfate out ofthe alumina. In case the acid sulfate of aluminium having sixteenmolecules of water of hydration is treated as described'then thechemical reaction that takes place in the vessel A is as follows:

which I prefer to use as pure as can be conveniently obtained, for moreor less calcium sulfate or potassium chlorid is apt to be present and toaffect the quality of the products formed by giving rise to potassiumsulfate, potassium carbonate, and calcium chlorid or calcium sulfate inthe products. The sodium chlorid is added in a quantity equivalentchemically to thesulfuric acid combined with the alumina and alsocontained invthe impurities present in the sulfate of aluminium, such assulfates of iron, and the sodium chlo- In either case it is first mixedwith the sodium chlorid,

rid and the sulfate of aluminium, together with the impurities containedtherein, are thoroughly and intimately mixed. This may be done toadvantage by adding the sodium chlorid to the sulfate of aluminium insolution just before evaporation is completed or by mixing the twotogether with a limited quantity of water and evaporating to such adegree of dryness as will enable the mixture to be readily subjected tothe next stage in the vessel A; but care must be taken that thetemperature does not rise above about 100 centigrade during this stageof the process. The evaporation referred to may be accomplished inshallow leaden pans I, set in the outletfiue B, to be heated by thewaste heat from the fire-box D. The mixture of sodium chlorid andsulfate of aluminium is then shoveled into the vesselA, to be treated asdescribed.

In case the sulfate of aluminium is impure the mixture must be mixedwith a sufficient quantity of carbonaceous matter, such as charcoal-dustor coal-dust, to reduce the sulfates formed to sulfids. The amount ofthe carbonaceous matter is calculated and added during the evaporationof the mixture in the leaden pans, or it may be added afterward andground up with the mixture of sodium chlorid and sulfate of aluminiumbefore this mixture is placed into the vessel A It is understood thatmore or less steam is passed through the pipe H into the vessel A,according to the amount of combined water in the sulfate of aluminium,it being understood that the less of such water the more steam isrequired until all the hydrochloric acid is expelled.

In case impurities, such as sulfates of iron, are in the sulfate ofaluminium then the apparatus shown in Fig. 2 is preferably employed,which apparatus consists of a vessel A", arranged in the brickwork Bhaving an outlet-flue B and the said vessel A is heated by the productsof combustion from the burning fuel on a grate C in a fire-box D, havinga steam-boilerE' for supplying steam by the pipes b the vessel A and forsupplying steam by the pipes H to the reverberatory furnace-hearth J,arranged in the brickwork B between the fire-box D and the vessel A Apipe F connects the vessel A with a condensation-chamber G, and the flue13 connects by valved branch pipes B B with combustion-chambers K and K.The reaction in the vessel A in addition to that occurring in the vesselA is as follows:

all iron, if any, are then decomposed as follows by the action of heatin the vessel A WVhen the sulfate of aluminium is impure and it isdesired to remove the iron oxid, then the resultant mass from the vesselA is transferred to the reverberatory furnace J, in which thetemperature of the mass is raised to a red heat and into which furnacejets of steam are introduced by the pipes H to come in contact with themass whenever required. The carbonaceous matter present at thetemperature mentioned reduces the sulfate of sodium to sulfid of sodium,which with the oxid of iron in the presence of alumina and steam formssodium aluminate and sulfid of iron. Thus,

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There may be an excess of sodium sulfid, depending upon the amount ofoxid of iron present.. Any excess of such sodium sulfid may be convertedinto caustic soda, and so into sodium aluminate, if there is enoughalumina present to combine with it by passing a jet of hot steam throughand over the charge. The reaction is as follows:

in case there be any alu mina at this stage free to combine with thecaustic soda. Now the mixture of sodium aluminate and impurities,

sulfid of iron, &c., is lixiviated, and the aluminate of soda and excessof caustic, if any, are recovered. The alumina may now be precipitatedfrom this solution in hydrated form in any of the ways usually employedin making alumina by means of sodium aluminate; but it is best, too, ifthe caustic be in excess and when it is not desired to use the causticover again to precipitate the solution by means of carbon-dioxid gas,thus forming carbonate of soda, as well as hydrated alumina, both ofwhich can now be recovered in any of the usual ways in common use in theart. The carbon dioxid needed for this purpose can be obtained byigniting the carbon monoxid formed in reducing the sulfate of sodium tosulfid of sodium by means of the carbonaceous material used in thecharge.

The sulfureted hydrogen formed in the furnace may be ignited to sulfuror to sulfur dioxid and recovered. Any sulfid of sodium remaining insolution maybe got rid of by crystallizing the carbonate of soda fromthe lye, which should be concentrated by evaporation after theprecipitated alumina is re.- moved.

It is understood that other substances besides those described may beused and allied reactions may take place without deviating r of sulfateof aluminium containing sulfate of from my invention. For instance,basic sulfates of aluminium, also anhydrous acid sulfate of aluminium,may be used with steam, and sodium chlorid and chlorid of potash may beused instead of chlorid of sodium.

' Sulfates of iron and sodium chlorid may he used to form hydrochloricacid, sodium sulfate, and oxid of iron. and sodium chlorid may beemployed with water of crystallization or steam to form sodium sulfateand either magnesium chlorid or magnesium oxid and hydrochloric acid.

Having thus described my invention, I claim as new and desire to secureby Letters Patent l 1; The herein-described process for the manufactureof alumina and by-products, consisting in mixing sulfate of aluminiumwith sodium chlorid and some water, to form a thick pulp,-then heatingthe latter to a temperature of from 200 to 300 centigrade andsimultaneously passing steam into the pulp to form a mixture of aluminaand sodium sulfate and to evolve gaseous hydrochloric acid with thesteam, and finally separating the alumina and sodiiim sulfate, as setforth.

2. The herein-described process for the manufacture of alumina compoundsand byproducts, consisting in subjecting a mixture iron, sodium chloridand carbonaceous material to the action of heat and steam, to evolvegaseous hydrochloric acid with the steam, and to form a mixture ofalumina, sodium sulfate and iron oxid, and then raising the temperatureof the latter mixture to a red heat in a reverberatory furnace, as setforth. t

3. The herein-described process for the manufacture of alumina compoundsand byproducts, consisting in subjecting a mixture of sulfate ofaluminium containing sulfate of iron, sodium chlorid and carbonaceousmaterial to the action of heat and steam, to.

evolve gaseous hydrochloric acid with the steam, and to form a mixtureof alumina, sodium sulfate and iron oxid, then raising the temperatureof the latter mixture to a red heat in a reverberatory furnace, andsimultaneously applying steam, as set forth.

4:. The hereindescribed process for the manufacture of alumina andby-products, consisting in mixing sulfate of aluminium containingsulfate ofiron with sodium chlorid, carbonaceous matter and some water,to form a thick pulp, then heating the latter and simultaneously passingsteam into the pulp to form a mixture of alumina and sodium sulfate andiron oxid and to evolve gaseous hydrochloric acid with the steam thenraising the temperature of the mixture to red heat in the presence ofsteam to produce sodium aluminate and sulfid of iron, then lixiviatingthe mixture of sodium aluminate and sulina in hydrated form, as setforth.

Magnesium sulfate- 5. The herein-described process for-the manufactureof alumina and by-products,

consisting in mixing sulfate of aluminium with sodium chlorid in aquantity equivalent chemically to the sulfuric acid contained in thesulfate of aluminium, then gradually heating the mixture to about 200 to300 centigrade and subjecting the mixture to the action of steam toevolve gaseous hydrochloric acid mixed with the steam,and to form-amixture of alumina and sodium sulfate, then condensing the hydrochloricacid andsteam, and separating the alumina and sodium sulfate bydissolving the latter out of the alumina, as set forth.

6. The hereindescribed process for the manufacture of alumina andby-products, consisting in mixing hydrated sulfate of alumina withsodium chlorid in a quantity equivalent chemically to the sulfuric acidcontained in the hydrated sulfate of alumina, then gradually heating themixture to about 200 to 300 centigrade to evolve gaseous hydrochloricacid and to form a mixture of alu-- manufacture of alumina and byproduots,

consisting in mixing sulfate of aluminium with sodium chlorid and somewater to form a thick pulp, then heating the latterand simultaneouslypassing steam into the pulp toform a mixture of alumina and sodium sul-Y fate and to evolve gaseous hydrochloric acid with the steam, andfinally separating the alumina and sodium sulfate, as set forth.

9. The herein -described process for the, manufacture of alumina andby-products,

consisting in mixing sulfate of aluminium with sodium chlorid in aquantity equivalent,

chemically to the sulfuric acid contained, in the sulfate of aluminium,then gradually heating the mixture and subjecting the mixture to theaction of steam to evolve gaseous hydrochloric acid mixed with the steamand t to form a mixture of alumina and sodium sulfate, then condensingthe hydrochloric acid and steam and separating the alumina and sodiumsulfate by dissolving the latter out of the alumina, as set forth.

10. The herein-described process for the manufacture of alumina andby-products, consisting in mixing hydrated aluminium sulfate with sodiumchlorid in a quantity equiv alent chemically to the snlfu ric acidcontained in the hydrated sulfate of aluminium, then gradually heatingthe mixture to evolve gaseous hydrochloric acid and to form a mixture ofalumina and sodium sulfate, then condensing the hydrochloric acid andseparating the alumina and sodium sulfate by dissolving the latter outof the alumina, as set forth.

11. The herein-described process for the manufacture of alumina andby-products, consisting in mixing sulfate of aluminium containingsulfate ofiron with sodium chlorid, carbonaceous matter and some water,to form a thick pulp, then heating the latter and simultaneously passingsteam into the pulp to form a mixture of alumina and sodium sulfate andiron oxid and to evolve gaseous hydrochloric acid with the steam, thenraising the temperature of the mixture to a red heat to produce sodiumaluminate and sulfid of iron, then lixivi'ating the mixture of sodiumaluminate and sulfid of iron, and finally precipitating the alumina inhydrated form, as set forth.

12. The herein-described process for the manufacture of aluminacompounds and byproducts, consisting in subjecting a mixture of sulfateof aluminium containing compounds of iron, sodium chlorid andcarbonaceous material to the action of heat and steam, to evolve gaseoushydrochloric acid with the steam, and to form a mixture of alumina,sodium sulfate and iron oxid, and then raising the temperature of thelatter mixture to a red heat in a reverberatory furnace, as set forth.

13. The herein-described process for the manufacture of aluminacompounds and byproducts, consisting in subjecting a mixture of alumcake and sodium chlorid and carbonaceous material to the action of heatand steam to evolve gaseous hydrochloric acid with the steam and to forma mixture of alumina, sodium sulfate and impurities, then raising thetemperature of the latter mixture to a red heat in a reverberatoryfurnace, as set forth.

14. The herein-described process for the manufacture of aluminacompounds and byproducts, consisting in subjecting a mixture of alumcake, compounds of iron, sodium chlorid and carbonaceous material to theaction of heat and steam to evolve gaseous hydrochloric acid with thesteam and to form a mixture of alumina, sodium sulfate and impuritieswith iron oxid, then raising thetemperature of the latter mixture to ared heat in a reverberatory furnace, as set forth.

In testimony whereof I have signed my name to this specification in thepresence of two subscribing Witnesses.

LUCIUS RICHARD KEOGII.

Witnesses:

ELIZABETH GILLIEs, HARRY DURRAND.

